<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        *{
            margin: 0;
            padding: 0;
        }
    </style>
</head>
<body>
<canvas id="canvas"></canvas>
<script id="vertexShader" type="x-shader/x-vertex">
    attribute vec4 a_Position;
    attribute vec2 a_Pin;
    varying vec2 v_Pin;
    void main() {
        gl_Position = a_Position;
        v_Pin=a_Pin;
    }
</script>
<script id="fragmentShader" type="x-shader/x-fragment">
    precision mediump float;
    uniform sampler2D u_Sampler;
    uniform sampler2D u_Pattern;
    varying vec2 v_Pin;
    void main() {
        vec4 o=texture2D(u_Sampler,v_Pin);
        vec4 p=texture2D(u_Pattern,v_Pin);
        gl_FragColor=mix(o,p,0.2);
    }
</script>
<script type="module">
  import {initShaders} from './js/utils.js'
  import Poly from './js/poly02.js'

  const canvas = document.getElementById('canvas')
  canvas.width = window.innerWidth;
  canvas.height = window.innerHeight;

  const gl = canvas.getContext('webgl')
  const vertexShader = document.getElementById('vertexShader').innerText
  const fragmentShader = document.getElementById('fragmentShader').innerText

  initShaders(gl, vertexShader, fragmentShader)

  gl.clearColor(0, 0, 0, 1)
  gl.clear(gl.COLOR_BUFFER_BIT)

  const source =[
    -0.4, 0.8, 0, 1,
    -0.4, -0.8, 0, 0.0,
    0.4, 0.8, 1.0, 1,
    0.4, -0.8, 1.0, 0.0,
  ];

  const poly = new Poly({
    gl,
    source,
    type: 'TRIANGLE_STRIP',
    attributes: {
      a_Position: {
        size: 2,
        index: 0
      },
      a_Pin:{
        size: 2,
        index: 2
      }
    }
  })

  const originImg = new Image()
  originImg.src = './images/dress.jpg'

  const pattern = new Image()
  pattern.src = './images/pattern1.jpg'

  Promise.all([
    imgPromise(originImg),
    imgPromise(pattern),
  ]).then(() => {
    poly.maps = {
      u_Sampler: { image: originImg },
      u_Pattern: { image: pattern },
    }
    poly.updateMaps()
    render()
  })

  //渲染
  function render() {
    gl.clear(gl.COLOR_BUFFER_BIT);
    poly.draw()
  }

  function imgPromise(img){
    return new Promise((resolve)=>{
      img.onload=function(){
        resolve(img);
      }
    });
  }

</script>
</body>
</html>
